Mailing List flyrotary@lancaironline.net Message #41866
From: Tracy Crook <tracy@rotaryaviation.com>
Sender: <rwstracy@gmail.com>
Subject: Re: [FlyRotary] Re: direct drive- was Re: Anyone have an RD-1C for sale?
Date: Sun, 9 Mar 2008 16:39:10 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Bobby answered the "how much HP" question with the HP chart - Looked like 112 HP at 4000 to me which is the RPM I would target.  That was also with a stock manifold.  With an intake manifold optimized for 4000 and adding a few ponies for a less restrictive exhaust system, I think 120 is do-able.  And I think it could come in at least 50 lbs lighter than a Lyc O - 320.  Another 5 or more pounds off the prop too.  And that's normally aspirated.  Turboing to 150 HP would be conservative.
 
Only down side is the ~ 56 - 58" prop you would have to use.  That would cost some takeoff & climb performance.
 
Tracy  (why the hell am I talking people out of gear drives :>)

On Sun, Mar 9, 2008 at 4:02 PM, Bobby J. Hughes <bhughes@qnsi.net> wrote:
RX8 hp chart.


From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Russell Duffy
Sent: Sunday, March 09, 2008 3:14 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: direct drive- was Re: Anyone have an RD-1C for sale?

Sure, that can work but why not something completely different?   I want to see someone do a direct drive 2 rotor (maybe even turboed) in the right application and the RV-3 comes close.   That would be Kool!   
 
Hi Tracy,
 
Thanks for the comments, but you're not suckering me into this direct drive idea :-)  
 
You've mentioned this before, but I just can't see the benefit.  How much HP would a 2 rotor make at 3000, 3500, and 4000 rpm?  Anyone got a power chart handy?   Limiting the rpm of a rotary to direct drive speeds just seems unnatural to me. 
 
Another point about the single rotor is that I'm trying to make the RV-3 Sport Pilot compliant, and that will be easier to justify with a smaller engine.  Fortunately, I don't foresee any medical issues, but I'm also fooling myself into believing this will be my last airplane.  Please keep the laughter to a minimum :-)  
 
Rusty (heading south in less than 5 days)
 
PS- Just shoveled about 1000 lbs of snow from around the van.  I can easily see how people have heart attacks doing this.  And yes, still with Philips, but we just changed our name to Philips Healthcare.     

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